this might sound stupid
but if you want really loud just muffler delete?

I don't want overly loud. I think the Eisenmann sport would be too quiet and the race would be about right. I like the fact that the Supersprint setp does not require cutting the stock muffler off, so if the SS sport mufflers have a similar overall noise level, I may go that route.

The Eisenmann Race performance will be louder than the Supersprint Sport. The Eisenmann Race offers a nice deep throaty tone and is not too loud. I think some people get worried by the name "RACE" but Eisenmann designed the system to retain the class of the E9x M3's.